Process for preparing elastomers of ethylene and c{11 -c{11 {11 {11 alpha olefins

ABSTRACT

A process for polymerizing ethylene and higher alpha olefins in the presence of a catalyst comprising an alkyl aluminum and the reaction product of a vanadium oxyhalide and an alkyl titanate. The resulting elastomeric polymers have exceptional tensile strength and green strength.

United States Patent 91 Wagensommer et al.

[ 11 3,725,364 51 Apr. 3, 1973 154] PROCESS FOR PREPARING ELASTOMERS OF ETHYLENE AND C3- C10 ALPHA OLEFINS [75] Inventors: Joseph Wagensommer, Westfield; Richard J. Lauria, Metuchen; John H. Staih, Plainfield, all of NJ.

[73] Assignee: Esso Research and Engineering Company, Linden, NJ.

221 Filed: Sept. 10, 1971 21 Appl.No.: 179,546

Related U.S. Application Data [52]. U.S. Cl. ..260/80.78, 260/882 R, 252/429 C [51] Int. Cl. ..C08f 15/40, C08f 15/04 [58] Field of Search ..260/88.2 R, 80.78; 252/429 [56] References Cited UNITED STATES PATENTS 3,567,653 3/1971 Wagensommer ..252/429 Primary Examiner-James A.'Seidleck Assistant Examiner-Roger S. Benjamin Attorney-Leon Chasan [5 7] ABSTRACT A process for polymerizing ethylene and higher alpha olefins in the presence of a catalyst comprising an alkyl aluminum and the reaction product of a vanadium oxyhalide and an alkyl titanate. The resulting elastomeric polymers have exceptional tensile strength and green strength.

7 Claims, No Drawings PROCESS FOR PREPARING ELASTOMERS OF ETIIYLENE AND C -C ALPHA OLEFINS CROSS REFERENCES This application is a continuation-in-part of Ser. No. 31,871, filed May 4, 1970 and now abandoned which is a continuation-in-part of Ser. No. 667,051, filed Sept. 7, 1967 and now abandoned'which is a continuation-inpart of Ser. No. 613,727, filed Feb. 3, 1967 and now abandoned which is a continuation-in-part of Ser. No. 504,120, filed Oct. 23, 1965 and now abandoned, which in turn is a continuation-in-part of Ser. No. 464,862, filed June 17, 1965 and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a process for polymerizing ethylene and higher alpha olefins, preferably with a nonconjugated diene. More particularly, the invention relates to a novel catalyst used in the process comprising an alkyl aluminum and the reaction product of a vanadium oxyhalide and an alkyl titanate.

2. Description of the Prior Art It is well known that ethylene and higher alpha olefins, such as propylene can be copolymerized at low pressures with a catalyst composed of a vanadium compound in conjunction with an alkyl aluminum compound.

The problem being solved by the polymers of the present invention are related to production of a curable essentially elastomeric compound which can be extruded to form hoses and tubes which will retain their extruded configuration prior to curing. This ability is commonly known as green-s strength, which is more completely defined hereinafter.

SUMMARY OF THE INVENTION It has now been found that elastomeric polymers of ethylene and higher alpha olefins, preferably containing a non-conjugated diene polymerized therewith, may be produced by a process for polymerizing a mixture of ethylene and a C to C alpha olefin comprising contacting said mixture with a catalyst composition comprising: (a) an essentially one molar equivalent of an aluminum alkyl compound of the formula R AlX wherein R is independently selected from the groupv consisting of C C monovalent hydrocarbon radicals, X is a halogen having an atomic number equal to or greater than 17, m is an integer from 1 to 3 and the sum of m and n is equal to 3; in combination with (b) 0.05 to 0.8 molar equivalents of a polymerization catalyst component consisting essentially of the reaction product formed by mixing: (i) a vanadium oxyhalide wherein the halogen has an atomic number equal to or greater than 17; with (ii) a titanium compound having the formula Ti(OR) wherein R is a C C alkyl radical and the mole ratio of said vanadium oxyhalide to said titanium compound is in the range of 0.05 to 10 moles of vanadium oxyhalide per mole of titanium compound.

The polymerizable mixture of monomers preferably contains a nonconjugated olefin in sufficient quantity to produce an interpolymer having from 0.1 to 20 weight percent, based on the interpolymer, of the nonconjugated diene present therein. It is preferred that the interpolymer contain 30 to 90 weight percent, based on the interpolymer, of ethylene. The most preferred mixutre of monomer comprises ethylene, propylene and 5-ethylidene-2-norbornene.

DETAILED DESCRIPTION WITH PREFERRED EMBODIMENTS The vanadium compound which is used in this invention is a vanadium oxyhalide. The vanadium oxyhalide has the formula VOX wherein X is a halogen having an atomic number equal to or greater than 17, i.e., chlorine, bromine, or iodine. The preferred vanadium oxyhalide is VOCl It is to be noted that vanadium tetrahalides such as VCl which are frequently used as a catalyst component for the copolymerization of alpha olefins, have no use in this invention.

The titanium compounds of this invention have the general formula Ti(OR) where R is a C -C alkyl radical. Preferably, R is a C -C alkyl radical. Thus, R may bean ethyl, propyl, butyl, pentyl, isopentyl, octyl, or hexyl groups. Most preferably, R is a butyl group so that tetrabutyl titanate is the most preferred titanium compound.

The alkyl aluminum compound which is useful in this invention has the formula R AlX, wherein R is a C C monovalent hydrocarbon radical, X is a halogen having an atomic number equal to or greater than 17 (i.e., Cl, Br, or I) or a C,-C monovalent hydrocarbon radical, m is an integer between 1 and 3 inclusive, and the sum of m plus n is equal to 3.

Specific examples of R and/or X groups include methyl, ethyl, propyl, n-butyl, n-amyl, isoamyl, phenyl, tolyl, and cyclopentyl radicals. Preferred are the C -C alkyl groups such as ethyl and butyl groups. Most preferred is ethyl. The preferred halogen is chlorine.

Examples of suitable alkyl aluminum compounds include triethyl aluminum, tripropyl aluminum, triisobutyl aluminum, diethyl aluminum chloride, ethyl aluminum dichloride, and aluminum sesquichloride. Most preferred is diethyl aluminum chloride. Mixtures of alkyl aluminum compounds can also be suitably used.

About 0.05 to 10 moles, preferably 0.15 to 3.0 moles of vanadium compound are reacted per mole of titanium-compound; andabout 0.05 to 1.0 mole, preferably 0.10 to 0.80 mole of the reaction product is utilized per mole ofaluminum alkyl compound.

The catalyst of this invention is used to copolymerize ethylene and a C -C alpha olefin. The C -C alpha olefin may be linear or branched where the branching tent is relatively high (above about 75 percent), they have some of the properties of plastics and are often designated as plastomers.

It is to be understood that the term copolymer of ethylene and a C -,-C alpha olefin is meant to include such copolymers which additionally include about 01-20 wt. percent, preferably 1-15 wt. percent, of a nonconjugated diolefin to add unsaturation to the final product so that it may be conventionally sulfur-cured. Suitable diolefins include 5-methylene-2-norbornene, methyl norbomadiene, isopropenylnorbornene, S-ethylidene-2-norbornene, dicyclopentadiene, 4,7,8,9- tetrahydroindene, 1,5-cyclooctadiene, and 1,4-hexadiene. In this invention S-methylene-Z-norbornene and 5-ethylidene-2-norbornene are preferred. Most preferred is 5-ethylidene-2-norbornene.

In preparing and using catalysts according to this invention, all steps should be carried out in the absence of moisture, carbon dioxide or other harmful impurities. This end is readily accomplished by blanketing all of the raw materials including the catalyst components, monomers, and inert diluents with an inert gas such as dry nitrogen or argon. Preferably, all materials are purified, e.g., by drying, distillation, etc., prior to their use. The reaction temperature for the formation of the vanadium compound-titanium compound catalyst component is suitably room temperature. This temperature is not critical, however, and either lower temperatures (e.g., 45 F.) or higher temperatures (e.g., 100 F.) may be used, although in selecting a higher temperature, a factor to be considered is that the reaC- tion is exothermic.

The conditions at which the polymerization reaction is carried out can vary over a wide range. Generally, temperatures ranging from 40 to 150 C. can be used; however, temperatures ranging from to 60 C. are preferred. Pressures ranging from 0.0 to 1,000 psig can be employed in the polymerization reaction; however, pressures in the range of from about 15 to 300 psig are more generally used. The reaction times used in the formation of the copolymers depend in general upon the temperatures used. Generally, reaction times ranging from 1 minute to hours can be employed; however, it is more usual to use reaction times ranging from 5 to 60 minutes.

The reaction vessel can be constructed of any material that is inert to the reactants and diluents used, and is capable of withstanding the operating pressures. Reaction vessels made of glass, stainless steel and glasslined steel are quite satisfactory. Details of the polymerization process have been generally described in the art; see for example, copending application no.

The copolymers of this invention are rubbery, or at least contain a substantial amount of amorphous material, and may be cured to useful vulcanizates. Where the copolymer has no unsaturation, i.e., does not contain a diolefin monomer, it may be cured with the use of certain free radical generators such as organic peroxides, e.g., dicumyl peroxide, or selected haloaliphatic compounds, e.g., octachlorocyclopentene. Where the copolymer contains unsaturation, conventional sulfur cures are possible. Generally, the copolymers have a viscosity average molecular weight in the range of 30,000 to 1,000,000 as determined by intrinsic viscosity in decalin solution at 135 C.

Various solvents may be used in the practice of this invention and they include aliphatic, naphthenic, aromatic, and halogenated hydrocarbon solvents, or an excess of the higher alpha olefin such as propylene may be used. Examples of solvents include n-hexane, propane, cyclohexane, toluene, xylenes, tetrachloroethylene, decalin, and chlorobenzenes. Preferably, n-hexane is used.

A variety of oils, carbon blacks, clays and silicas may be used as filler for the rubbers produced by this invention. The carbon blacks which are useful include high, medium or low structure SAF, SRF, HAF, FEF Blacks, and MPC blacks, all of which are commercially available. The amount of carbon black used can be from zero to 300 parts by weight, but preferably zero to 200 parts per parts of elastomer is used. From zero to 250 parts by weight of oil can also be added to obtain the desired balance of physical and processing properties in the final compound.

An unusual feature of this invention is that the copolymer produced with this novel catalyst can be cured to a high tensile strength material when the carbon black filler has a relatively large particle size. Specifically, it has been found that tensile strengths in excess of 900 psi are obtained when the cured polymer contains to 300 parts by weight of a carbon black (having an average particle size in the range of 0.01 to 0.5 microns) and 50 to 150 parts by weight of an extender oil.

An additional feature of this invention is that copolymers (including terpolymers) are produced which have unusually high green strengths. The green strength of a polymer is related to its tensile strength before curing. A high green strength insures a minimum of cracking of the polymer when it is pulled from the mill by an extruder. Additionally, a high green strength facilitates the fabrication of articles, such as molded hose, where the uncured elastomer compound is forced onto a mandrel, by eliminating creasing at high stress points. Furthermore, better dimensional control of extruded profiles is provided by minimization of collapse. Thus, copolymers of relatively high green strength, insofar as they do not crack, crease, or collapse, are more easily and economically processed.

Green strength was measured in psi by the following test. A 4 X 6 inches single cavity mold was preheated and then lubricated on both mold surfaces. Fifty-five grams of the uncured copolymer compound containing: 100 parts of polymer (rubber), 200 parts per 100 parts of rubber (phr) of SRF black, 100 phr of oil, 1 phr of stearic acid, 5 phr of zinc oxide was placed in the mold with its grain lengthwise. The mold was placed in a carver press set at F. The platens were then closed and the load increased in three steps up to 24,000 lbs. within 45 seconds. The mold was held under pressure for an additional 75 seconds after which the heat was turned off and water was circulated through the platens until they cooled down to room temperature. The pressure was then released and the compound removed from the mold. The compound pad was then relaxed for about 20 minutes at 25 C., after which the tensile strength was obtained on a Scott Tester at 20 inches/minute in accordance with ASTM Test No. D-4l2-66 at 25 C.

Green strengths of at least about 200 psi and higher are desirable and are easily achieved by means of this invention. Preferred are copolymers with a green strength of at least 250 psi.

It has been found that the green strength of copolymers made according to this invention is related to the low but controlled degree of crystallinity of the polymer which is a function of the weight percent of ethylene in the polymer. Thus, copolymers prepared according to this invention and containing at least about 70 wt. percent of ethylene will have a green strength in the desirable range (i.e., about 200 psi or higher). Copolymers containing about 72-75 wt. percent of ethylene will have even higher green strengths (in the range of at least about 250). The green strength continues to rise with the proportion of ethylene in the copolymer, although when more than about 80 wt. percent of ethylene is in the copolymer, other processing characteristics are not optimal.

Copolymers produced with conventional catalyst systems do not show this degree of correlation between ethylene content and green strength.

Copolymers produced with various catalyst systems will exhibit different crystallinity levels for essentially the same composition. Therefore, the preferred ethylene level will depend upon the nature of the catalyst system used. As shown in the examples, the crystallinity should be in excess of about 2 weight percent, to achieve green strength of over about 200 psi.

The invention and its advantages will be better understood by reference to the following examples, where all ethylene compositions were measured by'use of the correlation described. by H. V. Drushel and F. A. Iddings in Anal. Chem. 35, 28-33 (1963).

EXAMPLE 1 A reaction product of VOCl and tetrabutyl titanate was formed specifically as follows: Equal weights of VOCl and Ti(O-Butyl) were dissolved in n-hexane to make a 1.0 g/lOO m1. catalyst solution. This'formed a homogeneous solution and was accompanied by a significant heat effect apparently due to the formation of a new catalyst complex. This reaction product was added to the reactor with diethyl aluminum chloride and used to polymerize a mixture of ethylene, propylene and, 5- methylene-Z-norbornene in a weight ratio of 1/3/0.08. In a control experiment the same monomers in the same ratio were polymerized with a mixture of diethyl aluminum chloride and VOCl which was not reacted with a titanium compound. The results are shown in Table I.

60 SRF (20' at 320F.) (IStearic Acid, -Zn0,

5Zn0, l-Tuads, 0.5-Captax, 1Sulfur) Tensile, psi 2700 2560 Elon ation, 520 460 200 Modulus 850 I050 Shore A Hardness 71 71 Scorchlllasticity /50 9/77 Garvey Extrusion Inches/Minute 49 33 Rating 3443 2343 200 FEF/IOO Oil (20' at 320F.) (l-Stearic Acid, S-ZnO, 1.5-Tuads, 0.5-Captax', 1.5-

sulfur) Tensile, psi 750 1260 Elongation, 130 210 100% Modulus 680 700 Shore A Hardness 84 ScorchlPlasticity 8/67 8/68 Garvey Extrusion Inches/Minute 88 75 Rating 4444 4444 Tetramethylthiuram disulfide Mercaptobenzotl-iiazole MS-270, minutes to 3 point rise ML-212(1+8') In accordance with ASTM Test No. D-412-66 EXAMPLE 2 Example 1 was repeated with the use of different catalyst compositions of this invention. The results are shown in Table 11 below:

TABLE [I COMPARISON OF CATALYST SYSTEMS Run C D ML-2l2 50 60 Wt. C 53.2 65.0 Wt. Diene 2.9 2.9 Catalyst 0.016;

Cocatalyst 0.107;

0.085 moles Et,Al,Cl, Et AlCl 200 FEE/ Oil (20 at 320F.) (l-Stearic Acid, S-ZnO, 1.5-Sulfur) Tensile, psi 950 1 Elongation, 190 240 100% Modulus 620 600 Shore A Hardness 79 78 Scorch/Plasticity 7/84 14.5/72 Garvey Extrusion Inches/Minute 70.0 78.3 Rating 4444 4444 Contained 1.5 phr of tetramethylthiuram disulfide. in the curing recipe, 0.5 Captax Contained 1.5 phr of Monex (tetramethylthiuram monosulfide) in the curing recipe, 0.5 Altax (mercaptobenzothiazole sulfide) EXAMPLE 3 The following data were obtained to show the differences between terpolymers produced with the catalyst of this invention as compared with a catalyst of the prior art (i.e., YOCI with diethyl aluminum chloride). The differences relate to molecular weight distribution, ethylene distribution, and distribution of the diene in the terpolymer. The terpolymers which are analyzed in the data below are those which were formed in Example 1. Table 111 represents a control and Table IV relates to the terpolymer of this invention. The viscosity average molecular weight was determined by intrinsic viscosity in decalin at C.

TABLE III VOCI IEt AICI TERPOLYMER(CONTROL) Cumulative Mole Wt. Diene M.W. X 10 Ethylene I 11.2 53.8 3.04 s 15.3 56.7 2.64 15 19.4 26 22.6 61.5 3.14 26.4 33 30.7 66.3 3.04 35.2 35 40.2 71.3 3.41 43.1 49 46.1 72.2 3.61 49.1 56 52.3 73.7 3.6l 55.5 66

TABLE IV VOCl -Ti(O-Bu),/Et AlCl TERPOLYMER Cumulative Mole Wt. Diene M.W. X

Ethylene 8.4 65.6 3.74 8 13.3 68.3 3.86 28 17.1 28 20.2 70.1 4.23 23.8 50 28.5 70.0 4.16 31.1 69.4 3.97 34.0 97 37.1 69.4 3.85 40.5 103 44.0 70.8 4.03 47.6 122 51.5 71.0 3.85 54.7 160 58.3 72.9 3.92 61.9 187 65.4 72.9 3.96 68.9 220 72.2 72.7 3.98 75.4 255 78.8 73.0 3.94 82.0 295 84.7 73.2 3.67 86.8 378 88.4 73.8 3.64 89.8 485 91.5 72.9 3.28 93.3 73.8 3.06 710 94.8 73.8 2.95 810 97.7 74.6 2.83 825 98.1 685 EXAMPLE 4 To show that VCl is not useful in this invention, the following experiment was performed. VCl and Ti(O- Butyl) were mixed in n-hexane solvent and a black precipitate formed. The reaction product, in combination with aluminum diethyl chloride, when contacted with the monomers of Example 1, had no catalytic activity and no polymer was formed.

EXAMPLE 5 To show that copolymers of high green strength can be produced with the catalyst of this invention, the following experiment was performed. A reaction product of VOCl and tetrabutyl titanate was prepared as in Example I. This reaction product was added to the reactor together with 0.096 moles of aluminum diethyl chloride and used to polymerize a mixture of ethylene, propylene, and 5-methylene-2-norbornene (MNB) in a weight ratio of 1/3/0.08. The results are shown in Table V.

TABLE V Run No. 1 2 3 Tem rature, C. 35 26.5 Cata yst Cone, 1b./100 lb. Hexane 0.0065 0.006 0.007 Ethylene, Wt. 74.6 75.3 72.9 MNB, Wt. 2.7 2.7 2.6 200 FEF/lOO Oil( at 320F.)(l-Stearic Acid,5-ZnO, l.5-Sulfur) Tensile, psi( 1) 1665 1890 1800 Elongation, 180 215 230 Extrusion Rate, Inches/Minute 85 75 Mooney Scorch at 270F., T 12.8 10.9 11.3 Mooney Plasticity at 212F. 92 106 106 Green Strength, psi 320 370 270 compounded with, in addition to above, 1.5 phr tetramethyl thiuram disulfide and 0.5 phr mercaptobenzothiazole.

As can be seen from the last line of the table above, very high green strengths are achieved with this invention.

EXAMPLE 6 Example 5 was repeated with the exception that 5- ethylidene-Z-norbornene was substituted for the methylene norbornene. Equally good green strengths were obtained and the resulting copolymer had an additionally desirable property in that there was less interaction with carbon black during processing.

EXAMPLES 7-1 1 A series of five catalyst compositions were prepared and used in the polymerization of a mixture of ethylene, propylene and 5-methylene-2-norbornene (MNB). The polymers produced were compounded, as follows, and tensile strengths determined in a standard manner in accordance with ASTM Test No. D-412-66.

Component Parts Polymer FEF Black 100 Flexon 886 (oil) Stearic acid 1 ZnO 5 Tetramethyl thiruam disulfide 3 Mercapto benzothiazole 0.5 Sulfur 1.5,

The compounded rubber from each preparation were separately mixed in a Banbury Mill for 5 minutes at 240F. Tensile pads were prepared and cured for 20 minutes at 320 F.

The series of comparative runs was made to demonstrate the inapplicability, to the present invention, of catalyst systems commonly used in preparing crystalline, thermoplastic polymers, of ethylene and C -C alpha olefins. In particular, the teachings of US. Pat. No. 3,173,901 were used as a basis of the comparative catalyst preparations. The results are shown in Table VI.

The catalyst compositions were prepared as below:

7. (in accordance with the present invention) the first component of the catalyst system was made by mixing 2.0 moles of VOCl and 1.0 mole of tetrabutyl titanate. Upon mixing the reactants (which were originally at room temperature), substantial heat of reaction was observed immediately and the tempera ture of the reaction mixture increased. The reaction product so formed was used as catalyst together with 12.9 moles of diethyl aluminum chloride.

8. This composition was prepared by-mixing 2.0 moles of VOCl and 1.0 mole of TiCL. Upon mixing, the mixture showed no evidence of heat of reaction. There was then added 12.9 moles of aluminum triethyl.

9. A catalyst mixture was prepared as in Example 8 with the addition of 2 weight percent, based on total catalyst composition of SiC1 10. The catalyst composition of US. Pat. No. 3,173,901 was prepared according to Example 1 of the patent.

11. The catalyst composition of US. Pat. No. 3,173,901 was prepared according to Example 2 of the patent.

In each of the above Examples 7-11, the catalyst was fed to a polymerization reactor as a solution in n-hexane in amounts sufficient to make a solution containing 0.333 grams of total catalyst per 100 ml. of hexane solution. There was admitted to each reaction vessel (per 100 parts of n-hexane diluent) 3.2 parts of ethylene, 10.0 parts of propylene, and 0.20 parts of methylene-Z-norbornene (MNB). 0.0149 parts of catalyst plus 0.0333 parts of the alkyl aluminum also were admitted to the reactor. During the reaction, the mixture was maintained at a temperature of 26.5 C.; with vigorous agitation being provided. The nominal residence time in the reaction was 13.3 minutes; and at the end of this period, the reaction was terminated by quenching with 0.5 parts of isopropyl alcohol. After the reaction had been terminated by addition of the alcohol, the reaction mixture was heated to 100 C. to flash off the n-hexane diluent. The residual polymer crumb was hot milled to dryness and the products so obtained were subjected to analysis.

TABLE VI Tensile Strength (psi) Example It is apparent that the tensile strength of the product prepared by the present process, 2,010 psi, is substantially greater than the tensile strengths of the polymers produced by other, known catalyst systems of mixed transition metal compounds.

In addition to the tensile properties of the polymers produced above, tests were conducted to determine the heat of melting of the polymers. This was done by differential thermal analysis (DTA) using a DTA calorimeter. The test was conducted at a rate of C.

per minute.

Polymer produced in Example 7 had a heat of melting (AH) of 0.0 calories/gram, while the polymers produced with the catalysts of Examples 8-11 exhibit AI-Is in excess of 3.0 calories/gram. The Example 9 product had a All of 3.8 cal/gram. The distinct areas of melting shown in these tests, exhibited by the polymers of Examples 8-1 1 are attributable to long sequences of ethylene.

EXAMPLE 12 To show that the green strength of the copolymer is not appreciably affected by the catalyst concentration, or the polymerization temperature, the procedure of Example 5 was repeated except that the ethylene and propylene feed rates were varied as shown. The MNB feed rate was the same as in Example 5.

Table VII shows results achieved with a polymerization temperature of 95 F., and Table VIII shows results achieved with a polymerization temperature of 80 F.

TABLE VII (F) Green C H C H Catalyst feed Wt. C strength Run No. 113/ lb. 1b./ 100 lb. in polymer psi Hexane Hexane l 3.0 5.5 0.0055 72.0 270 2 3.0 6.3 69.7 3 3.0 4.7 72.3 230 4 2.8 3.8 0.0065 72.7 305 5 2.8 3.2 76.2 345 6 2.8 2.7 78.0 390 7 3.0 4.0 0.0085 70.5 180 8 3.0 3.4 71.6 270 9 3.0 2.8 77.0 380 10 2.8 3.6 0.007 74.4 300 TABLE VI" (80F) Green C,H C l-l, Catalyst feed Wt. C strength Run No. lb./l00 lb. lb./l00 lb. in polymer psi Hexane Hexane 11 3.0 4.3 0.0055 74.5 395 12 3.0 3.4 78.0 525 13 3.0 4.9 73.6 300 14 3.0 5.5 0.0065 68.0 70 15 3.0 4.5 69.9 16 3.0 3.6 73.8 345 17 3.0 3.5 0.0085 71.2 18 3.0 3.0 72.5 270 19 3.0 2.5 75.8 420 20 3.2 4.6 0.0060 75.3 400 EXAMPLE l3 Commercially available elastomeric copolymers produced with conventional catalysts were tested for green strength when compounded with 200 parts of black and 100 parts of oil. As can be seen from the table below, these copolymers did not have high green strengths even when their ethylene content was high.

TABLE IX Green Wt. Polymer Wt. C,H,Strength Crystallinity pm This invention 70-78.0 200- 500 2-15 Royalene 302 74.4 173 1.2 Nordel 1145 74.0 59 1.0 As determined from calorimeter heats of fusion. "See Tables VII and VIII.

"A commercially available terpolyrner of ethylene, propylene and about 1 mole percent of a third monomer (believed to be dicyclopentadiene). A commercially available terpolymer of ethylene, propylene and agout )1 mole percent of a third monomer (believed to be 1,4-hexa rent:

This invention has been described in connection with certain specific embodiments thereof; however, it should be understood that these are by way of example rather than by way of limitation, and it is not intended that the invention be restricted thereby.

What is claimed is: v

1. A process forpolymerizing a mixture comprising ethylene and a C to C alpha olefin which comprises contacting said mixture with a catalyst composition comprising:

a. an essentially one molar equivalent of an aluminum alkyl compound of the formula R,,,A1X, wherein R is independently selected from the group consisting of c o monovalent hydrocarbon radicals, X is a halogen having an atomic number equal to or greater than 17, m is an integer from 1 to 3 and the sum of m and n is equal to 3; in combination with pound is tetrabutyl titanate.

3. The process of claim 1 wherein said aluminum alkyl compound is diethyl aluminum chloride.

4. The process of claim 1 wherein said vanadium oxyhalide is VOCl 5. The process of claim 1 wherein said C to C alpha olefin is propylene.

6. The process of claim 1 wherein the mixture being polymerized additionally contains a nonconjugated diene.

7. The process of claim 6 wherein the nonconjugated diene is S-ethylidene-2-norbornene.

* III 

2. The process of claim 1 wherein said titanium compound is tetrabutyl titAnate.
 3. The process of claim 1 wherein said aluminum alkyl compound is diethyl aluminum chloride.
 4. The process of claim 1 wherein said vanadium oxyhalide is VOCl3.
 5. The process of claim 1 wherein said C3 to C10 alpha olefin is propylene.
 6. The process of claim 1 wherein the mixture being polymerized additionally contains a nonconjugated diene.
 7. The process of claim 6 wherein the nonconjugated diene is 5-ethylidene-2-norbornene. 